Questions tagged [beam]
Questions about the theory and applications of structural elements designed to resist bending.
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Why does concentrated shear force on a beam influence the whole beam?
This might be a silly question but can someone explain how this shear force on the right side of the beam causes Qy throught the whole beam?
I understand it mathematically but not conceptually so I ...
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0answers
93 views
Simple beam deflection of cantilever beam
Recently I had need to prove the beam deflection equation for a simple cantilever beam with a point load at the end. The equation would be in reference to the Euler-Bernoulli theory taught in most ...
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2answers
55 views
Simple beam with cantilever ends
I'm trying to find the maximum bending moment and deflection for this symmetrical simple beam. The formulae I can find, deal with either cantilever beams with one fixed end, or continuous beams ...
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2answers
117 views
Statically indeterminate fixed-pinned beam problem
F=32KN; Mf1=60KN-m; Mf2=-58KN-m; g=30KN/m I need to solve this using Force method. Find the reaction at the pinned end.
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2answers
209 views
Stiffness of a cantilever beam
I am working on calculating the stiffness of a cantilever beam by applying a distributed load. I wanted to ask if the distribution of the load on the beam effects its stiffness.
For eg., if I apply a ...
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vote
1answer
20 views
Can bending moments for a combination of loads on a simple beam, be calculated by adding the individual B.M. of each load?
This problem is about bending moment of a simple beam subject to a mixture of 4 or 5 UDLs and point loads. The beam is assumed to be rigid enough that deflection of the combined load is "small".
...
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2answers
91 views
Indeterminate beam with a guide at each end
I've been battling with a statics question (as attached) and can't for the life of me figure it out.
I've attempted removing the left side guide joint so then there are only 3 reactions and it should ...
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votes
2answers
43 views
Shear force and bending moment for continuous span
It's given that L1 = 5m, L2 and L3= 7.5m, w = 8.9kN/m , I am asked to find the bending moment using these coefficient.. Prior to this , i need to have the value of shear force first.Shear force = ...
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28 views
Possible improved approaches to 6mx3m moment-resisting frame with eccentricity+torsion, in advance of detailed engineer discussion
I'm putting a steel frame in, to "open plan" the rear of a brick cavity-wall terrace house in the UK, which will then have a single storey extension added behind it.
I have already retained a ...
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votes
1answer
50 views
Shape Functions of beam element with 3 nodes (quadratic element)
For a two node beam element there are four shape functions for four degree of freedom:
For a straight three node beam element how shape functions are?
Please note that beam is straight and not ...
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votes
1answer
21 views
Big Beam LVL or Glu Lam load capacity to support a gymnast
I need help knowing if I am selecting the correct wood beam.
The load will be all near the center and a 250 pound man will be doing pull ups on it. I would estimate a 1,000 pound dynamic load to be ...
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0answers
42 views
What is the optimal shape of a beam subject to three point bending?
Assume we have a beam with density $\rho$ that is subject to three-point bending according to the image above. The beam cross section is rectangular with the variable height $H(x)$ and constant width $...
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1answer
35 views
Calculation of natural frequency in a hinged beam
What I tried: Using the conjugate beam method to find deflection and hence stiffness of the beam, but I am unable to find reactions in the conjugate beam.
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0answers
53 views
Derivation of Bimetallic Strip Stress in Roark's Formulas
I am trying to understand some analytic expressions given in the handbook Roark's Formulas for Stress and Strain for bimetallic strip stresses. Namely, Roark's Formulas give the formulas
$$\text{...
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votes
1answer
57 views
Torsional rigidity D vs torsional rigidity factor k vs torsion constant J
I have a physics background so apologize my ignorance.
I'm confused by the constants $D$, $\kappa$, and $J$ when it comes to torsion of beams. From what I understand $\kappa$ and $J$ are the same ...
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vote
1answer
17 views
Supporting flexible square plate of uniform density in equilibrium with only 4 rolling contacts placed along the square's diagonals
Consider a flexible square of uniform density with vertices (0,0), (0,1), (1,0), (1,1). I need the 4 coordinates for rolling contacts along the diagonals that will stably support it. Someone could ...
3
votes
1answer
89 views
How to measure the unbraced length of lateral torsional buckling for negative moment in a W-shape steel beam?
I have a W-shape steel beam that is fixed-fixed and the top flange is fully braced for lateral torsional buckling. The negative moment at the end controls the design and there is no lateral bracing ...
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4answers
149 views
How does stiffness/rigidity affect the bending moment of a beam
My question may sound silly as it’s mainly good sense but I may be mixing things up.
Let’s consider a flexible cantilever beam of a given length and material is fixed at one end and free at the other ...
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votes
2answers
64 views
Why two identical beams without being pinned together will share half of the bending moments?
As shown above, two identical rectangular beams are placed and NO pinned together. I know each beam has its own neutral surface but why they carry half of the bending moments? I thought the bending ...
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vote
1answer
34 views
What's the second moment of a T beam with a heel? [closed]
The second moment of area of a rectangle is $I_{yy} = \dfrac{bh^2}{12}$
b : base
h : height
What is the second moment of area of a T beam like this one?
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0answers
36 views
How much (uniformly distributed) weight can this L beam support without bending? [closed]
As you can see in the picture, the L beam is 1in x 1/2in x 1/8in thick x 72in long and is made of ASTM A36 steel. It's bolted onto a vertical upright on both ends.
What is the maximum uniformly ...
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1answer
48 views
Abaqus Failure for I-Beam Section in Major direction only
For my 4th year dissertation in Civil Engineering I've got to investigate the difference between BS5950, Eurocode 3 and ABAQUS failures. The only thing is, in the BS5950 and Eurocode 3 the failure can ...
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2answers
60 views
Resulting torque on the cross section
I have trouble solving part A of the question. I thought the resulting torque would just be 10k * L of the beam.
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1answer
58 views
Which container orientation, if any, can hold more weight?
These are cross sections of identical shipping containers, except one is rotated 45 degrees. The cross sections are squares, 3 meters to a side. I drew dashed lines to show where they're suspended by ...
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vote
2answers
102 views
Neutral axis in canteliver beam at support
First, I thought the neutral axis would just be the y bar which can be obtained from the centroid of the cross-section but is different. I have tried letting the net moment at the wall = 0 and the ...
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votes
1answer
80 views
Should one use multiple elements through the thickness with multiple materials?
To get realistic results from a FEM calculation, it is common (or so I've been taught by someone who may not be up to date) to use at least four or five elements through the thickness of a beam or ...
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0answers
111 views
How to add Beam cross section properties to imported mesh in Ansys?
Ansys Workbench 17.1
I have a mesh that was imported from Abaqus into Ansys but the beam cross section data is missing. As a result the structural model omits the beam elements.
How do I access the ...
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votes
2answers
223 views
Deflection of a cantilever beam composed of separate (not bonded) planks
In the case of a simple cantilever beam having a uniform shape and being loaded at its end - the calculation of the deflection at any point along the beam is well known.
What happens if we split it ...
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votes
2answers
74 views
Is is possible to use singularity function to expresse the horizontal forces ?
I know how to translate torques and vertical forces into singularity functions, but may i also express the horizontal forces with singular function? if yes then what would be that expression?
Here ...
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votes
1answer
70 views
Shear forces along a beam using singularity functions
$\newcommand{\a}[1]{\langle#1\rangle}$
As you can see, the left end of the beam is fixed, and a distributed load is applied to the beam. I calculated the shear forces by conventional means, but when I ...
2
votes
1answer
186 views
Bending equation and max deflection of UDL and multiple point loads
I have a beam, simply supported with 2 points loads and 2 UDLs. The loads are symmetric about the centre of the beam.
I've tried to derive an expression for the moment along the beam and then via 2 ...
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2answers
40 views
Loadcell / strain gauge sizing for a joist
I am looking to use some load cells (foil based type) to detect presence for home automation within in a room. I was looking to mount some loadcells to the joists for the floor (UK Based house so ...
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votes
2answers
370 views
What exactly is the thin wall assumption in regards to beam cross sections?
What does it mean with respect to calculating stresses on a beam undergoing loading and when should it be applied?
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1answer
130 views
Timoshenko Beam Theory for Quasistatic Cantilever Beam: Shear Term
I'm trying to determine the effect of shearing force on the deflection of a quasistatic cantilever beam. In his book, Theory of Elasticity, Timoshenko added the following term to the deflection:
$$\...
3
votes
2answers
42 views
How to find a beam for my (simple) application
I have a spanof 9m that I bridge with a (as yet unspecified) beam. From this beam hangs a load (a pipeline), right in the middle, of 4.295 kN. The beam is simply supported. I want to use an IPE steel ...
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votes
2answers
399 views
Ceiling mounted punching bag without compromising structure or floor above
This question is regarding the safest way of installing a heavy punching bag of 100 lbs from the basement ceiling. Above the basement ceiling is a wood floor. The goal is to sleep soundly at night ...
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1answer
56 views
How does the superposition principle relate to Bernoulli-Euler and Timoshenko beam theory? [closed]
I have a shaft with a bearing in each end, and a large eccentric mass covering the entire "free length" of the shaft.
The attachment of the eccentric mass is done using heat shrinking.
Without ...
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vote
3answers
740 views
Transfering moment through internal hinge
My professor says, the internal hinge can not transfer moment:
But can we calculate $\Sigma M_A=0$ for whole beam ( without cutting it or something) this way?:
$\Sigma M_A=0 ===\Rightarrow M_A+(D_y ...
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vote
1answer
52 views
Base Support for a Tree house
I am building a tree house in my backyard and it is going to be relatively simple. There are no parts that require drilling into the tree. The whole house is propped up by four 4x4 wood supports. I'm ...
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votes
3answers
77 views
Natural frequencies of an orthotropic bending beam with circular cross-section
I am trying to find an expression for the natural frequencies of an orthotropic bending beam with a circular cross-section. I have tried searching for some literature on this, but have so far been ...
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2answers
1k views
Multiple Varying cross section beam deflection
How do we calculate the deflection of a cantilever with two or three cross-sections, and different forces acting at the end of each section?
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1answer
98 views
Beam Span for Outdoor Shelter [closed]
I'm building an outdoor shelter and I'm wondering what would be:
The maximum beam span for the type of wood/material used such it can support the roof weight and not sag in the middle,
Suggestions on ...
3
votes
1answer
121 views
Skewing of joints using virtual work
Given ist the following framework:
$$E=210 \frac{\text{kN}}{\text{mm}^2}$$
$$ EA \to \infty $$
$$ I_1 = 80000\text{cm}^4 $$
$$ \frac{I_1}{I_2} = \frac{3}{4} $$
$$ I_3=I_1 $$
Using the principle of ...
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2answers
113 views
Engineering mechanics(statics) [closed]
I don’t get how to get the answer to part e. Should we assume reactions at A and B in all three figures are same? If so, why?
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2answers
487 views
Beam deformation under trapezoidal load
Can somebody help me find the equation for the deformation of a simply supported beam under trapezoidal load (with intensity Q1 and Q2, at starting point X1 and end point X2)?
I am trying to find it ...
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0answers
707 views
Equivalent spring of beam supported by springs
My professor gave us yesterday a problem to calculate the equivalent spring of the system shown in the attached figure. The problem: a cantilever beam supported by two springs $k_1$ and $k_2$ located ...
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votes
3answers
50 views
Support columns inside metal tubing
Does structural metal tubing (e.g., either as HSS, or in space frames, or even motorcycle/bicycle frames) ever come with any small metal rods or columns inside of the tubing itself?
While it might ...
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0answers
526 views
Simply Supported beam with multiple point loads and distributed load [closed]
How can I solve this problem using FEM (longhand calculation)? I want to find deflections at each load point. This is not a homework problem. This is related to a project that I and my brother is ...
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1answer
1k views
Transfer of moments in beams with internal hinges
We have a beam with 1 internal hinge just like the picture. We know the internal hinge can not transfer moments between AB and BD. We know the 30 kN force makes some moments on BD & AB. If B (...
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votes
1answer
92 views
Why are steel I-beams mostly symmetrical?
From what I understand most types of steel are strong both in tension and compression, yet they are still usually significantly stronger in tension. Suppose a common I-beam supported on both ends and ...
